Recently, the sea-bottom has become of interest to scientists, to ore searchers and for waste storage purposes. In the latter case, waste must be sealed in torpedo-shaped containers, which are then dropped in suitable places to the sea-bottom. The weight and the shape of the containers are chosen such that high terminal velocities and consequently a considerable depth of container penetration into the sea-bottom sediment at a water depth of up to 5 or 6 kilometers are achieved.
It is fundamental for this concept that the hole created by the penetration of the container into the sediment fills up again behind the container and contributes to the sealing of the container. This requirement is absolutely necessary, as, over a period of several hundred years, the container will inevitably leak. If this happens, no material must be washed out of the container and reach the surface of the sediment. The closing of this hole is thus of essential importance for this kind of studies.
The filling-up of the hole depends on the geotechnical data of the sea-bottom, especially of the sediment layer into which the container penetrates.
Due to the water depth of up to 6000 meters, the penetration of the container into the sediment layer can hardly be directly observed by an underwater camera. In any case, such an underwater camera would only show the situation at the surface of the sediment but not in the body of the sediment. Also a test boring in the hole area after the penetration of the container would not supply reliable results, as one cannot be sure that the test boring has been made along the hole axis. This applies in particular as one cannot be quite sure whether the container has penetrated exactly vertically into the sediment. It is thus necessary the fix a measurment device at the rear end of the container, which measures certain physical characteristics of the hole area. This device must run along the hole through which the container has penetrated into the sediment layer and must transmit the impedance data through an antenna via acoustic signals to a receiver at the water surface.